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An epidemic (from ancient Greek ἐπί epí 'to, at, to' and δῆμος dēmos 'people'), also known as a plague , is a temporally and locally limited increased occurrence of illnesses with a uniform cause within a human population and thus corresponds to a large outbreak of a disease . The term is not limited to infectious diseases .

In epidemiology , an epidemic is used when the number of new cases of illness ( incidences ) increases over a certain period of time in a certain region. A distinction is made between explosive and tardive epidemics according to the rate at which the incidence of the disease increases. If it spreads across countries and continents, it is referred to as a pandemic . A decrease in the incidence of the disease is called regression . On the other hand, an endemic is defined as the continually increasing occurrence of a disease in a localized population; the incidence remains approximately the same, but is higher than in non-endemic areas.

Since the ending -demie linguistically refers to people, the terms epizootic instead of epidemic and panzootic instead of pandemic are also common in veterinary medicine .

Word origin

The word epidemic , adjective epidemic , is the 18th century Germanized form of a borrowing from Middle Latin epidemia , adjective epidemos 'native' , this from Greek ( Doric ) ἐπιδᾶμος epidᾱmos 'spread among the people'; to ἐπιδημία epidēmía 'stay in one place' or ἐπιδήμια [νόσος] epidēmia [nósos] '[disease] spread among the people' with the composition of ἐπί epí 'on, at, to' and δῆμος dēmos 'people'.

The German word plague ( Middle High German  siuche ) is derived from the adjective faint . It runs the importance spreading disease 'now more common for growing epidemic of animal diseases (eg. As foot-and-mouth disease which spread nationwide often called) used epidemic is called.

Types of epidemics

In general, a distinction is made between the following types of epidemics:

  • Epidemic via a generally accessible medium : An epidemic whose pathogens originally spread via a generally accessible medium (vehicle), e.g. B. air, drinking water, food have spread.
  • Explosive epidemic: The explosive epidemic is an epidemic with a sudden increase in the number of diseases. Often these types of epidemics are associated with certain transmission factors, e.g. B. These are infections that are transmitted through food or drinking water . The latter is called a water epidemic.
  • A tardive epidemic (lat. Tardus / tardivus "slow", "late", "belated", also contact epidemic) is an epidemic with slowly but steadily increasing numbers of illnesses. In a tardive epidemic, infections and illnesses through direct human-to-human contact increase (e.g. through droplet infections , contact infections , or sexually transmitted diseases ). Alongside the explosive epidemic, the tardive epidemic is one of the two classic basic types of epidemic. The term was introduced by Karl Kißkalt . In contrast to the term contact epidemic, the tardive epidemic is intended to characterize the temporal course of an epidemic in the same way as the explosive epidemic; Tardive epidemics can be due to long incubation times , pathways of infection that only lead to the infection of a single person ( sexually transmitted diseases ), a low number of carriers, an accumulation of immunity (e.g. due to previous latent or manifest infection) or the Interaction of various factors. Diseases that can lead to a typical tardive epidemic are, for example: plague , smallpox , flu, HIV .
  • Mixed epidemic : A mixture of an explosive epidemic and a tardive epidemic, in which the infection process is explosive at first, but a tardive epidemic develops over time.
  • Small-scale epidemic : An accumulation of incidences in a spatially limited milieu (e.g. in a home, children's facility or school).
  • Complex epidemic : An epidemic induced by multiple pathogens.
  • Graft Epidemic : An epidemic resulting from an endemic .
  • Point source epidemic : An epidemic in which pathogens have spread briefly and simultaneously from a point source.
  • Provocation epidemic: An epidemic that emerged after activation of latent infections as a result of a decrease in resistance in the population.
  • Litter epidemic : Increased incidence of infections in different places with a common cause (e.g. due to population movements or food transport).
  • Sum epidemic: An epidemic that arises from an endemic situation through a summation of infections ( wave of compaction, wave of attraction) because susceptible individuals have accumulated and a pathogen with a high level of contagiousness is spreading.
  • Shipping epidemic : Due to the shipping of contaminated food, food-borne infections are increasing in various places, the connection between which may be difficult to identify.
  • Pseudo epidemic : A pseudo-epidemic , even apparent epidemic also quotient epidemic called an apparent epidemic that by locally increased incidence of cases of infectious disease that an increased manifestation of infections caused by a sudden increase in the susceptibility of a decline in the population or by increased diagnostic activity and not by real increase in infections is triggered. The term pseudo-epidemic was coined by Bernhard de Rudder , whereas the term quotient epidemic was coined by Ulrich Friedemann . De Rudder distinguished between “real epidemics” and “pseudo-epidemics” with real increases in the number of infections and pseudo-epidemics, which are just fluctuations in interference.

Examples of epidemics

The epidemic diseases include various tropical diseases such as dengue , but also, for example, cholera , flu , typhoid and polio . In the past, anthrax epidemics occurred more often in the downstream area of ​​tanneries. Probably the most devastating epidemics in human history were caused by the plague ; including the Black Death and the Justinian Plague .

Cases of illness and death (black) in the course of the Ebola virus epidemic in West Africa up to July 2014

The Ebola fever epidemic 2014 to 2016 in West Africa and the Ebola fever epidemic 2018 to 2020 in the east of the Democratic Republic of the Congo are also examples of epidemic outbreaks of Ebola fever in terms of the number of cases and the time course .

In the case of influenza, one speaks of an influenza wave when over 10% of the population is infected in different regions during one season. The US Centers for Disease Control and Prevention speaks of an influenza epidemic if the excess mortality rate from flu and pneumonia is more than 7.5 percent higher than an average winter in a particular winter .

In the case of chlamydiosis , a sexually transmitted disease hardly known among adolescents in this population group , there is also talk of a secret epidemic .

Epidemiological description

In contrast to an endemic - in which a disease occurs continuously within a population with approximately the same number of cases (reproduction rate = 1) - an epidemic spreads with a higher reproduction rate (> 1). In the case of an infectious disease, this means that the number of infected people increases and the number of new infections increases. The rate at which new infected persons appear through contact with infected persons is significant for the spread; at the beginning it corresponds to the basic reproduction number ( R 0 ). Initially, the number of new cases of infection per time interval increases by approximately the same percentage compared to the previous one and grows exponentially . The increase in new cases of infection in absolute numbers is therefore initially rather low and increases more rapidly as the events progress.

This dynamic development can be dampened if the number of infectious contacts is restricted - for example through quarantine or a changed social behavior with distancing and appropriate hygiene measures - and the number of second infections transmitted per case falls. With a net reproduction number ( R t ) ≤ 1, the number of newly occurring cases of illness no longer increases. If an epidemic cannot be contained during the course of the disease, it will only come about after the disease has spread to such an extent that the proportion of susceptible ( susceptible ), not yet infected individuals has been greatly reduced. As a result, the number of new infections continues to decrease after a while until the disease reaches an endemic status or dies out in the population.

Justus Hecker is considered the founder of historical epidemic pathology , who dealt with the history of epidemics such as the Black Death .


It is essential for the protection of the population to record the increased incidence of new cases of illness as early as possible. Many sufferers look for information about diseases on the Internet. The evaluation of the data by search engines can therefore provide clues to identify epidemics at an early stage. The evaluation of personal news services on the Internet can also be used for this evaluation. However, frequent searches for a disease or its mention on the Internet is not always the result of an increased prevalence or incidence of that disease. Exaggerated forecasts can therefore be made if other additional data sources are not included in the assessment.

Societal handling of epidemics in history

The cultural scientist Joseph Vogl quotes Michel Foucault , who describes three ways of dealing with epidemics in history: The government reacted to leprosy in the Middle Ages with banishing, segregating and excluding the sick ; In the face of the plague in the early modern period, she developed strategies of surveillance and confinement , then also disciplinary mechanisms , control networks and meticulous observation of individuals; They responded to smallpox from the end of the 18th century with vaccination measures , immunity strategies , statistical surveys and risk assessments . In view of the AIDS epidemic, homosexuals were initially persecuted and 'risk groups' were denounced; later, the handling of the epidemic shifted more to areas outside the closed area of ​​medical observation.

See also


  • Stefan HE Kaufmann et al. (Ed.): Is the risk of epidemics growing? Global Epidemics and Poverty: Strategies to Contain Disease Control in a Connected World. (= Fischer TB. No. 17664). S. Fischer Verlag, Frankfurt am Main 2008, ISBN 978-3-596-17664-9 .
  • J. Andrew Mendelsohn: From "Eradication" to Balance. How epidemics got complex after WWI. In: Christoph Gradmann , Thomas Schlich (ed.): Strategies of causality. Concepts of disease causation in the 19th and 20th centuries. (= Modern history of medicine and science. Volume 5). Centaurus Verlagsgesellschaft, Pfaffenweiler 1998, ISBN 3-8255-0173-6 , pp. 227-268.
  • Oliver Razum, Jürgen Breckenkamp, ​​Patrick Brzoska: Epidemiology for Dummies. 3rd, updated and revised edition. Wiley-VCH Verlag, Weinheim 2017, ISBN 978-3-527-71269-4 .
  • Jacques Ruffié, Jean-Charles Sournia: The epidemics in human history. 4th enlarged edition. Translated from the French by Brunhild Seeler. Klett-Cotta, Stuttgart 2000, ISBN 3-608-94001-4 .
  • Julius Rosenbaum : History of the lust epidemic in antiquity for doctors, philologists and antiquity researchers. Hall 1839; 7th, revised edition, enlarged with an appendix, Verlag von H [ermann] Barsdorf, Berlin 1904 (title: History of the lust epidemic in antiquity together with detailed studies on the Venus and phallic cults, brothels, Νοῦσος ϑήλεια of the Scythians, paederasty and other sexual ones The debauchery of the ancients is represented as contributions to the correct explanation of their writings. ) Reprint: Central antiquariat of the German Democratic Republic, Leipzig 1971 (edition for S. Karger, Basel / Munich /…). Pp. 314-327 ( Genius epidemicus ).
  • Malte Thießen (ed.): Infected Europe. Epidemics in the long 20th century. De Gruyter Oldenbourg, Munich 2014, ISBN 978-3-11-036434-7 .
  • Manfred Vasold: Plague, hardship and severe plagues. Plagues and epidemics from the Middle Ages to the present day. CH Beck, Munich 1991, ISBN 3-406-35401-7 .
  • Jörg Vögele, Stefanie Knöll, Thorsten Noack (eds.): Epidemics and pandemics from a historical perspective. Springer VS, Wiesbaden 2016, ISBN 978-3-658-13874-5 .
  • Stefan Winkle : Cultural history of epidemics. Komet, Düsseldorf / Zurich 1997, ISBN 3-933366-54-2 (3rd, improved and expanded edition under the title Scourges of mankind. Cultural history of epidemics. Artemis & Winkler, Düsseldorf / Zurich 2005, ISBN 978-3-538- 07159-9 ).

Web links

Wiktionary: Epidemic  - explanations of meanings, word origins, synonyms, translations

Individual evidence

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